Multiply in your head :)

With this trick, you will be able to multiply any two numbers from 11 to 19 in your head quickly, without the use of a calculator.

Try this:

Take 15 x 13 for an example.

Always place the larger number of the two on top in your mind.
First add 15 (larger number) + 3 (units digit of the smaller number) = 18
Add a zero behind it (multiply by 10) to get 180.
Multiply the 3 (units digit of the smaller number) x 5 ( units digit of the bigger number) = (3x5= 15)
Add 180 + 15 = 195.

Wasn't that easy? Practice it on paper first!

Regards
10on10 team